“Extru-tech is using actual equipment that you would find in most petfood plants in a bio-hazard laboratory or a pilot plant,” said Jim Marsden, PhD, regents distinguished professor at Kansas State University. “Raw materials can be inoculated with Salmonella or other pathogens and the effect of the extrusion process can be exactly quantified. This process is a breakthrough for the petfood industry.”

Based on the design criteria, a BSL-2 pilot plant was outfitted with an E525 production-scale extruder system and the equipment was configured for the production of an industry-generic, low-moisture, dry-expanded petfood. The E325s typically used produce 200 to 600 pounds of petfood per hour, whereas the E525 chosen can produce nearly 8,000 pounds per hour (in terms of typical petfood). The industry-generic petfood formula selected was charged with a 3 serotype cocktail of Salmonella, an inoculant that represents typical contamination events in the manufacturing process.

All three replications of the challenge study resulted in a log reduction of Salmonella that exceeded the 5-log reduction requirement of a CCP allocation. Extru-Tech also discovered that many readily available and scientific methods of inoculation rendered a result that was not truly representative of a contamination event because of the method by which the raw material was inoculated.

“Extru-tech is documenting the parameters that are required to deactivate Salmonella in the extrusion process,” said Dr. Marsden. “There are other production steps that follow where Salmonella could recontaminate the product. Extru-tech is looking at those additional steps to identify interventions that could be applied downstream to prevent recontamination.”